Maps were my Grandma's love language. She always had an atlas handy and she would reach for it any time someone would talk about somewhere they had been.  

Map reading builds important spatial skills for children, it gives them a sense of where things are in their world. Where does Christopher Robin live in relation to Winnie the Pooh? Look in the front of the book. How does Dorothy get to the Emerald City? We know because L. Frank Baum included a beautiful map in his books. How far is it from the Beaver's Dam to Cair Paravel? C.S. Lewis made a map for that. "Gulliver's Travels," "Treasure Island," "The Princess Bride," all of these adventure books have maps in them. 

Some of the best adult books have maps in them. We can follow the escapades of Bilbo Baggins on the map in the front of "The Hobbit." Being able to see at a glance how close Guernsey is to France helps the reader understand how the events unfold in "The Guernsey Literary and Potato Peel Pie Society." "Lillian Boxfish Takes a Walk" by Kathleen Rooney has a fabulous map showing where Lillian takes her walk in southern Manhattan. I am not very familiar with Manhattan, and being able to see where she went made the book much more interesting. 

Other books with great maps include Madeline Miller's "Circe", "The Devil in the White City" by Eric Larson, "The Martian" by Andy Weir and "Pillars of the Earth" by Ken Follett.

In 2011 a friend of mine recommended that I read George R. R. Martin's series "A Song of Ice and Fire"- it's also known as "Game of Thrones." I protested that I don't enjoy fantasy, but she insisted. I caved and proceeded to read all five books totalling 4,197 pages that year. As I read, I found myself flipping to the maps in the front of the book. Where are these folks from? Where are they going? What is the land like where they live? The maps answered all of these questions. I had a difficult time keeping track of the hundreds of characters, until I got to the appendix of the first book to discover 18 pages of character lists with allegiances and some backstory. 

That's another thing I am happy to find in a book- a family tree. How are all these people related? Phillipa Gregory writes about English history. She makes it easy for the reader by providing family trees so you can keep the Yorks, Lancasters and Tudors straight. She also often includes maps in her books. Yaa Gyasi's "Homegoing" follows a family from 1775 through eight generations into modern times- you can use the family tree in the front of the book to keep track of who is who. Diana Gabaldon's books have hundreds of characters. Rather than providing a list in the back of the books she wrote two companion books with character lists in them to help readers keep everyone straight.

I think a map improves almost every book, and if you are reading a family saga, or a book with lots of characters, having a list of who's who makes it much easier on the reader. If the writer has built a world, a map helps the reader follow the adventure- just like my grandma.